Nonequalizing differential transmission



Feb. 29, 1944. R, RI RANDALL 2,342,755

'NONEQUALIZING DIFFERENTIAL TRANSMISSION Filed NOV. 26, 1942 Patented F eb. 29, 1944 UNITED STATES PATENT cEEicE;

NoNEQU-ALIZING pinnen-nitriet fTnANsn/nssrom "itap'h it. Randall, Fieept, iii. Application November 26, 1942. serial N9; 466,984

s claims. meme-13) -My invention relates to Va nonequal-iz'ing differential gearing 'which provides greater 'safety for automotive' vehicles because of a new action in power transmission.

It has been found in practice. that `the cori-r ventional diiferential is too eflicieht in vequalization. It differentiates not only for unequal wheel velocities as in turning a corner,- butV causes the power to flow to the 4wheel of least' resistance as occurs with 'unequal traction conditions, such as icy pavements, muddy soft shoulders, etc.

vFrein rthe standpclint of performance and safety the conventional diiferential leaves mu'ch ltobe desired. With unequal traction, the en- -gineapbwer flows to the wheel having the lesser traction. This constant changing of traction from one wheel to the otheradthen to both, causes irregular power liow with resultant danger of sideeslipi swayingand skiddingf. `It is this Acondition more so than unedualized br'akes\` that causesmotor vehclestoslip out of control, s'pecially with `bad highway and road 4conditions.

-One of the objects of my invention is to pro. 'vide a noneqalizing diierential'gearing which willv be useful in automotive transmissionsy which under `ordinary conditions will transmit torque from thepropeller shaft equally to two'drive axles, but which is' so designed that 'if one ofI the drive wheels slips for lack 'of traction, all or ain'jr proportion y'of' the torque will be transmitted 'to the 'nonslipping wheel and in whicha relatively long torq'u radius is provided vin the gearsv secured to the axles. n l y y A further objet of my invention 'is to provide such a constructionpwhich will have relatively few parts, 'which 'will be easy to assemble and in which use is made of a large part of the present standard gear construction in automotive differentials.

Further objects and advantages will appear from the specification and claims.

In the drawing, in which two forms of my invention are shown, f

Figure 1 is a sectional perspective vviewof a nonequalizing differential;

l Fig. 2 is a section substantially on the liney 2-2 of Fig. 1;

Fig. 3 is a section substantially on the line 3-3 of Figs. 1 and 2; and

Fig. 4 is a sectional View similar to the section shown in Fig. 1 but showing a diiferent form of gearing.

Referring first to Figs. 1, 2, and 3, they construction shown comprises a bevel gear l which gear i is secured, a pairof axles Semounted for relative rotation with respect to" the gea-r carrier Lia'pair of be'vel 'gearsl E, one spline'd on each 'axle 5, 'a pair of beif'el pinions'lf, one meshing' with each of the pair of 'bevel-gears iig-a pair `of 'shafts 8 rotatably mounted in the-gear carrier l on whichl the bevel pinions 1 are -Xedly se- 'curedfa pair of `worms "9 rotatable `with the shai'ts'ii,v respectively, a worin "g'ear I9 meshing with both worms, and a shaft HA yoir-Which the worin gear lil is mounted haying'its ends' mounted in thegear 'carrierl 4.

In use, if the vehicle is being driven in a 'straight 'line and there is 'no sl'i'ppagejb'etwen the'tires and the roadway, theK torque froni the fpropeller shaft 3 will be transmitted equally to the two axl'sfii and there will be no relative rotation be- 'tween the two aides, the `torque being transmitted from the bevel pinion 2 rthrough the bev'el gear I tothe cross shaft Il on Ywhi'h the'worm 'gear 'I0 is mounted. The resisting vcounte'rto'rdue l foin'eaoh of the axles '5 acts'thr'ourgh the. bevel geart, bevel pinion 'l and worm 9 'to exert a `counter-rotational "force on' the'correspbnding worin shaft 3, but as there is resisting counter'- tor'cie on both of the axles the torque from the prbpelleish'aft will betransmitted equally tothe two axles.

. n1; "case, due t the slippery cnditi'on or the roadway, or r'for 'any other reasonyth resisting euntertcrque en one ef the' should become such that the' traetive eirect of 'ene ofthe wheels becomes negligible' or terysmall, au, 'or the portion, of the td'e" will ben transmitted to the axle in which the resisting counti'tlirque is still effective, due to the substantially irreversible or at least nonequalizing eifect of the pitch of the threads of the worm gearing, the pitch being such that the gearing is either substantially irreversible or at least so steep that very little power will be transmitted when the worm gear is attempting to drive the worm. It has been found that on a nonequalizing differential the motive power can not cause one gear l, the two axle bevel gears 6, and the two bevel pinions 1 meshing therewith may be substantially the same as those used in the ordinary equalizing differential gearing. It will also be noted that the pitch diameter of the axle bevel gears 6 is comparatively large, thus giving a. relatively large torque radius which may be substantially the same as the torque radius used for these gears in present standard practice.

In Fig. 4 the construction is similar to that previously described, except that here two bevel pinions T are provided for each of the axle bevel gears, each bevel pinion being provided with its individual worm 9a, 9b, 9c, and 9d and two worm gears IOa and Ib being provided, each meshing with a pair of worms. In the construction of Figs. 1, 2, and 3, the direction of thread of the worms 9 is the same, whereas in the construction of Fig. 4 the direction of thread of the worm 9a. is the reverse of that of the worm 9b, and the direction of thread of the worm 9c is the reverse of `that of the worm' 9d.

It will b'e seen that the pitch of worms in Fig. 4 is such that the endwise force or thrust acting on the bevel pinions 1 due to their coaction with the bevel gears 6 is in the opposite direction from the end force or thrust on these bevel pinions due to the coaction of the worm gearing so that these end thrusts tend to balance each other and minimize the total end thrust enabling the use of comparatively simple and inexpensive end thrust bearings.

While I have lshown the gears 6 and 1 as bevel gears, it is possible that other types of gear might be used, such as helical hypoid gears, or the like, still retaining the relatively large pitch diameter of the gears 6 and the transverse axes of the gears 1.

Further modifications imll be apparent to those skilled in the art and it is desired, therefore, that the invention be limited only by the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. A nonequalizing diierential comprising a pair of rotatable substantially coaxially mounted traction drive elements, a pair of gears, one securedto each element and coaxial therewith, a pair of pinions, one meshing with each gear, the

axes of said pinions being transverse to the axis of said elements, a pair of worm gearing elements, one rotatable with each pinion, a worm gearing element lying between and meshing with both worm gearing elements of said pair, and a gear carrier rotatable about the axis of said drive elements on which said pinions and worm gearing elements are mounted.

Z. A nonequalizing differential comprising a pair of rotatable substantially coaxially mounted traction drive elements, a pair of bevel gears, one secured to ,each element and coaxial therewith, a pair of bevel pinions, one meshing with each bevel gear, the axes of said bevel pinions being transverse to the axis of said elements, a pair of worms, one rotatable with each bevel pinion, a worm gear lying between and meshing with both worms, and a gear carrier rotatabley about the axis of said elements on which said bevel pinions, worms, and worm gear are mounted.

3. A nonequalizing differential comprising a pair of rotatable substantially coaxially mounted traction drive elements, a pair of gears, one secured to each element and coaxial therewith, two pairs of pinions, one pair meshing with each gear, the axes of said pinions being transverse to the axis of said elements, two pairs of worms, one rotatable with each bevel pinion, two worm gears each lying between and meshing with a worm of both pairs, and a gear carrier rotatable about the axis of said elements on which said pinions, worms, and worm gears are mounted.

4. A nonequalizing diierential comprising a pair of rotatable substantially coaxially mounted traction drive elements, a pair of bevel gears, one secured to each element and coaxial therewith, two pairs of bevel pinions, one pair meshing with each bevel gear, the axes of said bevel pinions being `transverse to the axis of said elements, two pairs of worms, one rotatable with each bevel pinion, twoworm gears, each lying between and meshing with a worm of both pairs, and a gear carrier rotatable about the axis of said elements on which said bevel pinions, worms, and worm gears are mounted; Y

5. A nonequalizing `differential comprising a pair of rotatable substantially coaxially mounted traction drive elements, a pair of bevel gears, one securedto each element and coaxial therewith, two pairs of bevel pinions, one pair meshing with each bevel gear, the axes of said bevel pinions being transverse to the axis of said elements, two pairs of` worms, one rotata le with each bevel pinion, two worm gears, each meshing with a worm of both pairs, and a gear carrier rotatable about the axis of said elements on which said bevel pinions, worms, and worm gears are mounted, the pitch of the threads of the worms and worm gear being such that the end thrust on the worms due to the coaction of the worms and worm gear will be in the opposite direction to the end thrust on the worms due to the coaction of the bevel gears and bevel pinions.

RALPH R. RANDALL. 

